X-ray crystal structure studies will be undertaken on drugs which have clinical use or potential as drugs for central nervous system pathologies. The structures of 7-methyl-nor-diazepam and a new 1,3-benzodiazepine compound will be investigated. These agents are chemically related to diazepam but have markedly different anticonvulsant properties, and the comparison of their stereochemistries with those of diazepam, diphenylhydantoin, and the phenacemide derivatives so far structurally elucidated should allow us to better understand those stereochemical features responsible for the biological action of these anticonvulsants. Our structural determination of the copper-binding tripeptide, glyclglycyl-L-histidine methyl amide, a potentially valuable agent in the treatment of Wilson's disease, has shown the copper coordination to involve four nitrogens of the tripeptide and oxygen atom of another molecule. This finding suggests that a tripeptide with an amino acid having a side-chain oxygen function, such as aspartic acid, at the N-terminal might bind copper better through intramolecular five-coordination to the copper, and thus be of better clinical use. The synthesis of such a molecule is in progress, and we intend to investigate its structure and mode of copper-binding. BIBLIOGRAPHIC REFERENCES: The Stereochemical Basis of Anticonvulsant Drug Action. V. Molecular Structure of Sulthiame. A. Camerman and N. Camerman. Canad. J. Chem. 53, 2l94 (l975). Thyroid Hormone Stereochemistry. IV. Molecular Conformation of 3'Isopropyl-3,5-Diiodo-L-Thyronine in the Crystal and in solution. J. K. Fawcett, N. Camerman, and A. Camerman. J. Amer. Chem. Soc. 98, 587 (l976).